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Université de Fribourg

In situ measurements of calcium isotopes by ion microprobe in carbonates and application to foraminifera

Rollion-Bard, Claire ; Vigier, Nathalie ; Spezzaferri, Silvia

In: Chemical Geology, 2007, vol. 244, no. 3-4, p. 679-690

An analytical procedure has been developed for the in situ measurement of calcium isotope composition of carbonates with a spatial resolution of 15–20 μm on a Caméca IMS 1270 ion microprobe. By using two Faraday cup detectors, the ⁴⁰Ca and ⁴⁴Ca can be measured simultaneously, improving the internal reproducibility. Instrumental mass fractionation (IMF) of calcium isotopes was...

Université de Fribourg

Hyalinea marmarica, a new species of benthic foraminifera from the Sea of Marmara (Turkey)

Spezzaferri, Silvia ; Yanko-Hombach, Valentina

In: The Journal of Foraminiferal Research, 2007, vol. 37, no. 4, p. 309-317

Traditionally, the benthic foraminifera Hyalinea balthica (Schröter) has been considered a species with high intraspecific variability, possibly related to climatic changes, and, therefore, a potential indicator of paleoclimate in the Mediterranean Sea. However, a stable and characteristic morphology very different from the syntype of the species can be observed in specimens from the Sea...

Université de Fribourg

Dicarinella imbricata (Mornod 1949): First SEM documentation of the lost holotype and foraminiferal assemblage from the type horizon (Upper Cretaceous, Switzerland)

Caron, Michèle ; Spezzaferri, Silvia

In: Eclogae Geologicae Helvetiae, 2006, vol. 99, no. 3, p. 295-299

L’espèce de foraminifère Dicarinella imbricata, du Crétacé supérieur de Suisse, a été décrite par L. Mornod en 1949. L’holotype a été figuré seulement par des dessins de l’auteur, et l’holotype n’a jamais été déposé dans le domaine public. Comme l’holotype manquait depuis longtemps, il a été considéré comme perdu et un néotype a été créé. Cependant,...

Université de Fribourg

Turonian radiolarians from Karnezeika, Argolis peninsula, Peloponnesus (Greece)

Bandini, Alexandre N. ; Baumgartner, Peter O. ; Caron, Michèle

In: Eclogae Geologicae Helvetiae, 2006, vol. 99, no. Supplement 1, p. S1-S20

Near Karnezeika a roughly 140 m thick Upper Cretaceous section consists of interbedded pelagic limestones, cherts and coarse polymict breccias including ophiolites and shallow water limestones. At the base, pink pelagic limestones rest on deeply altered and fractured Lower Jurassic Pantokrator Limestone. This first pelagic facies is dated as middle Turonian, based on planktonic Foraminifera. Over...

Université de Fribourg

In situ measurements of Li isotopes in foraminifera

Vigier, Nathalie ; Rollion-Bard, Claire ; Spezzaferri, Silvia ; Brunet, Fabrice

In: Geochemistry Geophysics Geosystems, 2007, vol. 8, p. Q01003

In situ measurement of Li isotope ratios in foraminifera has been developed using a Cameca ims 1270 ion microprobe. In situ δ⁷Li analyses have been performed in biogenic calcite of planktonic foraminifera from various locations. Results show that for west Pacific mixed Globigerinoides and Globorotalia (22°S161°E), the isotopic variability between tests and within a...

Université de Fribourg

Scanning electron microscope documentation of the lost holotypes of Mornod, 1949: Thalmanninella reicheli and Rotalipora montsalvensis

Caron, Michèle ; Spezzaferri, Silvia

In: The Journal of Foraminiferal Research, 2006, vol. 36, no. 4, p. 374-378

The species Globotruncana (Rotalipora) reicheli and Gobotruncana (Rotalipora) montsalvensis, were established in 1949 by Mornod. The two holotypes were figured only by drawings and the specimens were never made publicly available. Since their first description, these two species have acquired great importance as biostratigraphic markers. However, holotypes had been considered as...

Université de Fribourg

Bolboforma (Phytoplankton Incertae Sedis), Bachmayerella and other Calciodinelloidea (Phytoplankton) from the Middle Miocene of the Alpine–Carpathian Foredeep (Central Paratethys)

Spezzaferri, Silvia ; Rögl, Fred

In: Journal of Micropalaeontology, 2004, vol. 23(2), p. 139

Bolboforma is a microfossil of uncertain origin with affinities to protophytic algae. It generally occurs at high latitudes and/or in cool and temperate waters and has a high stratigraphic potential especially for the Miocene. Calcareous cysts of dinoflagellates represent the ‘benthic cyst stage’ of unicellular organisms belonging to the marine phytoplankton.The occurrence of...

Université de Fribourg

The Aptian, Albian and Cenomanian of Roter Sattel, Romandes Prealps, Switzerland: a high-resolution record of oceanographic changes

Strasser, André ; Caron, Michèle ; Gjermeni, Maksim

In: Cretaceous Research, 2001, vol. 22 (2), p. 173

The Aptian–Lower Turonian hemipelagic sediments of Roter Sattel in the Swiss Prealps are well dated by planktonic foraminifera. Stacking pattern of the limestone-marl alternations and facies evolution allow the identification of sequence boundaries, transgressive surfaces, and maximum-flooding events or condensed sections on at least two hierarchical levels. Calibrated by a precise...

Université de Fribourg

Extreme climatic events and their evolution under changing climatic conditions

Beniston, Martin ; Stephenson, David B.

In: Global and Planetary Change, 2004, vol. 44, p. 1-9

This short introductory paper illustrates some key issues concerning extremes by focusing on daily temperature extremes defined using quantiles and threshold exceedances. The examples include both a low- and a high-elevation site in the Swiss Alps where long records of homogenous daily data are readily available. The analysis of extremes highlights several features, some of them taken from...

Université de Fribourg

Heterogeneous dynamics of coarsening systems

Mayer, P. ; Bissig, Hugo ; Berthier, L. ; Cipelletti, Luca ; Garrahan, J. P. ; Sollich, P. ; Trappe, Véronique

In: Physical Review Letters, 2004, vol. 93, p. 11570-11573

We show by means of experiments, theory, and simulations that the slow dynamics of coarsening systems displays dynamic heterogeneity similar to that observed in glass-forming systems. We measure dynamic heterogeneity via novel multipoint functions which quantify the emergence of dynamic, as opposed to static, correlations of fluctuations. Experiments are performed on a coarsening foam using...